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Abstract:

A pattern forming apparatus includes a first nozzle part 52 in which
discharge nozzles 523 for discharging an application liquid are arranged
in a row in a direction (Y-direction) perpendicular to a scan-moving
direction relative to a substrate, and a second nozzle part 72 including
a pair of discharge nozzles 723, the positions of which in the
Y-direction can be changed by a ball screw mechanism 740. A plurality of
pattern elements parallel to each other and having the same length are
formed by the discharge of the application liquid from the first nozzle
part 52 and, on the other hand, pattern elements having lengths different
from these pattern elements are formed by the second nozzle part 72, the
application of which is controlled at timings independent of the first
nozzle part 52.

Claims:

1. A pattern forming apparatus, comprising: a substrate holder that holds
a substrate; a first nozzle part in which a plurality of first discharge
ports for respectively discharging an application liquid containing a
material for forming pattern elements are arranged in a row; a second
nozzle part that includes a second discharge port for discharging the
application liquid; and a mover that moves the first nozzle part relative
to the substrate in a scan-moving direction perpendicular to an
arrangement direction of the first discharge ports and moves the second
nozzle part relative to the substrate in the scan-moving direction such
that the second discharge port passes at an outer side of the respective
first discharge ports in the arrangement direction, wherein the first
discharge ports and the second discharge port discharge the application
liquid at different timings.

2. The pattern forming apparatus according to claim 1, wherein the mover
moves the first nozzle part relative to the substrate in synchronization
with the discharge of the application liquid from the first discharge
ports and moves the second nozzle part relative to the substrate in
synchronization with the discharge of the application liquid from the
second discharge port.

3. The pattern forming apparatus according to claim 1, wherein the second
nozzle part changes and sets a position of the second discharge port in
the arrangement direction.

4. The pattern forming apparatus according to claim 3, wherein the mover
can change a relative movement amount of the second nozzle part with
respect to the substrate in the scan-moving direction according to the
set position of the second discharge port in the arrangement direction.

5. The pattern forming apparatus according to claim 1, comprising a
plurality of the second nozzle parts, the positions of the second
discharge ports of which differ from each other in the arrangement
direction.

6. The pattern forming apparatus according to claim 3, wherein a pair of
the second discharge ports are provided at the opposite sides of the
first nozzle part in the arrangement direction.

7. The pattern forming apparatus according to claim 6, wherein: the pair
of second discharge ports are arranged at positions symmetrical with
respect to the row of the first discharge ports; and the mover integrally
moves the pair of second discharge ports relative to the substrate.

8. The pattern forming apparatus according to claim 6, wherein the
application liquid is supplied to the pair of respective second discharge
ports from a same application liquid storage for storing the application
liquid.

9. The pattern forming apparatus according to claim 1, wherein the
application liquid is supplied to the plurality of first discharge ports
from a same application liquid storage for storing the application
liquid.

10. The pattern forming apparatus according to claim 1, wherein:
positions of the first nozzle part and the second nozzle part in the
scan-moving direction are fixed; and the mover realizes relative
movements of the first nozzle part and the second nozzle part with
respect to the substrate by moving the substrate holder holding the
substrate.

11. A pattern forming method for forming pattern elements by applying an
application liquid containing a material for forming the pattern elements
to a substrate, comprising: a step of moving a first nozzle part, in
which a plurality of first discharge ports for respectively discharging
the application liquid are arranged in a row, relative to the substrate
in a scan-moving direction perpendicular to an arrangement direction of
the first discharge ports, thereby forming a plurality of linear pattern
elements corresponding to the plurality of first discharge ports; and a
step of moving the second nozzle part including a second discharge port
for discharging the application liquid relative to the substrate in the
scan-moving direction such that the second discharge port passes at an
outer side of the respective first discharge ports in the arrangement
direction, thereby forming a linear pattern element, wherein the
application liquid being discharged at different timings from the first
discharge ports and from the second discharge port.

Description:

CROSS REFERENCE TO RELATED APPLICATION

[0001] The disclosure of Japanese Patent Application No. 2011-067040 filed
on Mar. 25, 2011 including specification, drawings and claims is
incorporated herein by reference in its entirety.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] This invention relates to a pattern forming technology for forming
predetermined pattern elements by applying an application liquid to a
substrate surface.

[0004] 2. Description of the Related Art

[0005] There is known a technology for forming a predetermined pattern on
a substrate by applying an application liquid containing a material for
forming pattern elements to the substrate and curing it. For example, a
technology disclosed in JP2010-278225A previously disclosed by the
present applicant is applicable to a technology for manufacturing a
photoelectric conversion device by forming wiring pattern elements on a
substrate having a photoelectric conversion surface. In this technology,
a multitude of stripe-shaped pattern elements parallel to each other and
having an equal length are formed on a substrate by scan-moving a nozzle
with a multitude of discharge ports relative to the substrate and
discharging an application liquid containing a pattern forming material
from the respective discharge ports.

[0006] Substrates for which pattern elements are to be formed by this type
of pattern forming technology come in various shapes. For example, some
of monocrystalline silicon substrates used as substrates of solar cells
have an octagonal shape obtained as if by cutting off four corners of a
square. This is for effectively utilizing the areas of circular
monocrystalline silicon wafers. The lengths of pattern elements to be
formed on such substrates are not necessarily constant.

[0007] However, the lengths of all the pattern elements formed by the
above technology are same. A technology for efficiently forming pattern
elements on a substrate having a non-rectangular shape (hereinafter,
referred to as an "irregularly shaped substrate") by application has not
been established yet thus far.

SUMMARY OF THE INVENTION

[0008] This invention was developed in view of the above problem and an
object thereof is to provide a technology capable of efficiently forming
pattern elements on an irregularly shaped substrate in a pattern forming
technology for forming predetermined pattern elements by applying an
application liquid to a substrate.

[0009] A pattern forming apparatus of the present invention comprises: a
substrate holder that holds a substrate; a first nozzle part in which a
plurality of first discharge ports for respectively discharging an
application liquid containing a material for forming pattern elements are
arranged in a row; a second nozzle part that includes a second discharge
port for discharging the application liquid; and a mover that moves the
first nozzle part relative to the substrate in a scan-moving direction
perpendicular to an arrangement direction of the first discharge ports
and moves the second nozzle part relative to the substrate in the
scan-moving direction such that the second discharge port passes at an
outer side of the respective first discharge ports in the arrangement
direction, wherein the first discharge ports and the second discharge
port discharge the application liquid at different timings.

[0010] According to the thus constructed invention, the plurality of
linear pattern elements parallel to each other and having an equal length
can be formed at one time by a scan-movement of the first nozzle part
similar to those disclosed in the above patent literature. Further, the
pattern element parallel to the respective pattern elements formed by the
first nozzle part and having a length different from these pattern
elements can be formed by a scan-movement of the second nozzle part and
the discharge of the application liquid at a discharge timing different
from the first nozzle part. By combining the application by the first
nozzle part and that by the second nozzle part, pattern elements can be
efficiently formed also on an irregularly shaped substrate having a
non-rectangular shape.

[0011] A pattern forming method of the present invention is a method for
forming pattern elements by applying an application liquid containing a
material for forming the pattern elements to a substrate and comprises: a
step of moving a first nozzle part, in which a plurality of first
discharge ports for respectively discharging the application liquid are
arranged in a row, relative to the substrate in a scan-moving direction
perpendicular to an arrangement direction of the first discharge ports,
thereby forming a plurality of linear pattern elements corresponding to
the plurality of first discharge ports; and a step of moving the second
nozzle part including a second discharge port for discharging the
application liquid relative to the substrate in the scan-moving direction
such that the second discharge port passes at an outer side of the
respective first discharge ports in the arrangement direction, thereby
forming a linear pattern element, wherein the application liquid being
discharged at different timings from the first discharge ports and from
the second discharge port.

[0012] In the thus constructed invention, pattern elements can be
efficiently formed also on an irregularly shaped substrate having a
non-rectangular shape similar to the invention relating to the pattern
forming apparatus described above. Note that, in this invention, there is
no limitation as to which of formation of the pattern elements by the
first nozzle part and that of the pattern elements by the second nozzle
part is performed first. That is, it does not matter whichever is
performed first. Further, formation of the pattern elements may be, for
example, either started or ended at the same timing by the first and
second nozzle parts.

[0013] The above and further objects and novel features of the invention
will more fully appear from the following detailed description when the
same is read in connection with the accompanying drawing. It is to be
expressly understood, however, that the drawing is for purpose of
illustration only and is not intended as a definition of the limits of
the invention.

BRIEF DESCRIPTIONS OF THE DRAWINGS

[0014] FIG. 1 is a drawing which shows a pattern forming apparatus
according to a first embodiment of the invention;

[0015] FIG. 2 is a diagram which shows structures of the first and second
nozzle parts;

[0016] FIG. 3 is a diagram which shows an example of a solar cell formed
using the pattern forming apparatus of FIG. 1;

[0017] FIG. 4 is a flow chart which shows a pattern forming process in
this pattern forming apparatus;

[0018] FIGS. 5A and 5B are views which diagrammatically show formation of
the pattern elements by the first nozzle part;

[0019] FIGS. 6A to 6C are diagrams which show the principle of the
application ending operation;

[0020] FIGS. 7A and 7B are views which diagrammatically show formation of
pattern elements by the second nozzle part; and

[0021] FIG. 8 is a diagram which shows an outline of a second embodiment
of a pattern forming apparatus according to this invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] FIG. 1 is a drawing which shows a pattern forming apparatus
according to a first embodiment of the invention. The pattern forming
apparatus 1 is an apparatus for forming conductive electrode wiring
patterns on the substrate W, such as a single-crystalline silicon wafer,
which has in its surface a photoelectric conversion layer, and
accordingly manufacturing a photoelectric conversion device which will be
used as a solar cell for instance. The apparatus 1 may for example be
used to form collector electrodes in the incident light-receiving surface
of a photoelectric conversion device, as a preferable application.

[0023] In the pattern forming apparatus 1, a stage moving mechanism 2 is
provided on a stand 11 so that the stage moving mechanism 2 can move a
stage 3 which holds the substrate W within the X-Y plane which is shown
in FIG. 1. Two frames 121 and 122 are mounted to the stand 11, straddling
the stage 3. A first head part 5 is attached to the frame 121, and a
second head part 7 is attached to the frame 122. The second head part 7
is away from the first head part 5 in the direction (+X), and the
distance between the first head part 5 and the second head part 7 is set
such that a distance between a first nozzle part and a second nozzle part
described later is wider than the length of the substrate W measured in
the X-direction.

[0024] The stage moving mechanism 2 comprises an X-direction moving
mechanism 21 for moving the stage 3 in the X-direction, a Y-direction
moving mechanism 22 for moving the stage 3 in the Y-direction, and a 0
rotation mechanism 23 for rotating the stage 3 about an axis which is
directed to the Z-direction. The X-direction moving mechanism 21 has a
structure that a ball screw 212 is linked to a motor 211 while a nut 213
fixed to the Y-direction moving mechanism 22 is attached to the ball
screw 212. A guide rail 214 is fixed above the ball screw 212. As the
motor 211 rotates, the Y-direction moving mechanism 22 smoothly moves
together with the nut 213 in the X-direction along the guide rail 214.

[0025] The Y-direction moving mechanism 22, too, comprises a ball screw
mechanism and a guide rail 224 so that as a motor 221 rotates, the ball
screw mechanism makes the θ rotation mechanism 23 move in the
Y-direction along the guide rail 224. A motor 231 disposed to the θ
rotation mechanism 23 rotates the stage 3 about the axis which is
directed toward the Z-direction. The structure described above makes it
possible to change the direction of relative movement of the first head
part 5 and the second head part 7 to the substrate W and the directions
of the first head part 5 and the second head part 7 to the substrate W. A
controller 6 controls the respective motors of the stage moving mechanism
2.

[0026] A stage elevating/lowering mechanism 24 is disposed between the 0
rotation mechanism 23 and the stage 3. In response to a control command
from the controller 6, the stage elevating/lowering mechanism 24 moves
the stage 3 up or down, whereby the substrate W is positioned at a
designated height (which is a position in the Z-direction). The stage
elevating/lowering mechanism 24 may be an actuator such as a solenoid and
a piezo-electric element, a gear, combined wedges, etc.

[0027] In a base 51 of the first head part 5, a discharge nozzle part 52
which stores a liquid-state (or paste-like) application liquid inside and
discharges the application liquid onto the substrate W and a light
irradiation part 53 for irradiating UV light (ultraviolet light) toward
the substrate W are disposed. More specific description about the first
nozzle part 52 is described later.

[0028] The light irradiation part 53 is connected to a light source unit
532 which generates UV light through an optical fiber 531. Although not
shown, the light source unit 532 comprises at its light emitting part a
shutter which can be opened and closed, and in accordance with whether
the shutter is open or closed and to which degree the shutter is opened,
the light source unit can control on/off and the amount of emitted light.
The controller 6 controls the light source unit 532.

[0029] A base 71, a discharge nozzle part 72 and a light irradiation part
73 are disposed to the second head part 7 similarly with the first head
part 5. The light irradiation part 73 is connected to an optical fiber
731 and a light source unit 732. Functions of the light irradiation part
73, the optical fiber 731 and the light source unit 732 are basically
same as those in the first head part 5.

[0030] FIG. 2 is a diagram which shows structures of the first and second
nozzle parts. As shown in a lower part of FIG. 2, the first nozzle part
52 provided in the first head part 5 includes a syringe pump 521 with an
inner hollow for storing the application liquid, a manifold part 522
internally provided with a buffer space BF communicating with the hollow,
and a plurality of discharge nozzles 523 arranged in a row in the
Y-direction on the lower surface of the manifold part 522. A discharge
port 525 communicating with the buffer space BF is provided at the lower
end of each discharge nozzle 523. Further, a plunger 524 is inserted in
the inner space of the syringe pump 521 and vertically driven by the
motor driven and controlled by the controller 6, an actuator such as a
solenoid, compressed air or the like.

[0031] In such a construction, the plunger 524 is pushed down in response
to a control command from the controller 6, whereby the application
liquid in the syringe pump 521 is pressurized to be pushed out to the
manifold part 522. The application liquid fed to the manifold part 522 is
continuously discharged from the discharge ports 525 of the respective
discharge nozzles 523 via the buffer space BF. That is, this pattern
forming apparatus 1 is a coater adopting a nozzle dispense method. The
amounts of the application liquid discharged from the respective
discharge ports 525 can be made uniform by discharging the pressure-fed
application liquid via the buffer space BF.

[0032] On the other hand, as shown in an upper part of FIG. 2, the inner
space of a syringe pump 721 for storing the application liquid
communicates with discharge ports 725 provided at the lower ends of a
pair of discharge nozzles 723, 723 via a pair of flexible hollow tubes
726, 726 in the second nozzle part 72. The respective discharge nozzles
723 are supported movably in a predetermined range in the Y-direction by
a ball screw mechanism 740 attached to the base 71. More specifically,
the ball screw mechanism 740 includes a motor 741, a ball screw 742
coupled to the motor 741 and extending in the Y-direction and a bearing
743 for supporting an end of the ball screw 742 opposite to the one near
the motor 741. Screw grooves of the ball screw 742 are formed in opposite
directions at the opposite ends, and nuts threadably engaged with these
screw grooves are united with the discharge nozzles 723.

[0033] Thus, when the motor 741 rotates in response to a control command
from the controller 6, the ball screw 742 rotates and, accordingly, the
discharge nozzles 723 move in the Y-direction. Since the directions of
the screw grooves threadably engaged with the nuts provided in the two
discharge nozzles 723 are opposite, the two discharge nozzles 723 move in
directions opposite to each other. Specifically, for example, when the
ball screw 742 rotates in a direction indicated by a broken line arrow in
FIG. 2, the two discharge nozzles 723 respectively move in directions
also indicated by broken line arrows, i.e. away from each other in the
Y-direction. Conversely, when the ball screw 742 rotates in a direction
indicated by a dotted line arrow in FIG. 2, the two discharge nozzles 723
respectively move in directions also indicated by dotted line arrows,
i.e. toward each other in the Y-direction. The two discharge nozzles 723
may be respectively independently driven by separate driving mechanisms.

[0034] The discharge ports 725 of the two discharge nozzles 723 are
located symmetrically with respect to a center axis (dashed-dotted line)
of the row of the discharge ports 525 of the first nozzle part 52 in the
Y-direction. That is, Y-direction distances D1, D2 from the center axis
to the respective discharge ports 725 are equal. Note that the two
discharge ports 725 are located at the same positions in the X-direction
and the Z-direction. Further, movable ranges of the discharge ports 725
by movements of the discharge nozzles 723 include outer sides of the
outermost discharge ports 525a located on the most outer sides in the row
of the discharge ports 525 of the first nozzle part 52.

[0035] The syringe pump 721 stores the application liquid in its inner
space and a plunger 724 is provided in this inner space. When the plunger
724 is pushed down in response to a control command from the controller
6, the application liquid stored in the syringe pump 721 is pressurized
and pushed out from the discharge ports 725 at the lower ends of the
discharge nozzles 723 via tubes 726. The application liquid can be
equally discharged from the respective discharge ports 725 by
pressure-feeding the application liquid from the single syringe pump 721
to the pair of discharge nozzles 723.

[0036] The application liquids may be a conductive pastes, or conductive
and photo-curing paste-like mixed liquids containing conductive
particles, an organic vehicle (namely, a mixture of a solvent, a resin, a
thickener, etc.) and a photo-polymerization initiator for instance. The
conductive particles may for example be silver powder which is a material
to make electrodes, and the organic vehicle contains ethyl cellulose,
which serves as a resin material, and an organic solvent. The viscosity
of the application liquids is preferably 50 Pas (Pascal seconds) or below
for instance before execution of hardening under irradiated light but
preferably 350 Pas or above after execution of hardening under irradiated
light. The compositions of the application liquids stored in the first
and second nozzle parts 52 and 72 may be the same, or alternatively, the
application liquids having different compositions from each other may be
stored in the respective nozzle parts.

[0037] By constructing the first nozzle part 52 and the second nozzle part
72 as described above, the following effects can be achieved in this
embodiment. First, since the first nozzle part 52 includes the plurality
of discharge ports 525 arranged in a row in the Y-direction, the
application liquid can be applied in stripes extending in the
X-direction, parallel to each other and having an equal length by moving
the first nozzle part 52 in the X-direction relative to the substrate W
while discharging the application liquid from the discharge ports 525. By
containing the photo-curing material in the application liquid and
irradiating light (e.g. UV light) from the light irradiation part 53 to
the application liquid immediately after application, stripe-shaped
pattern elements can be formed by curing the application liquid
immediately after application while maintaining its cross-sectional
shape.

[0038] Also in the second nozzle part 72 separate from the first nozzle
part 52, stripe-shaped (linear) pattern elements extending in the
X-direction can be formed by moving the second nozzle part 72 in the
Y-direction relative to the substrate W and irradiating light from the
light irradiation part 73 while similarly discharging the application
liquid from the discharge ports 725. At this time, since application by
the second nozzle part 72, more specifically on/off timings of the
discharge of the application liquid can be controlled independently of
the first nozzle part 52, pattern elements having lengths different from
the pattern elements formed by the first nozzle part 52 and having an
equal length can be formed.

[0039] In this pattern forming apparatus 1, relative movements of the
first and second nozzle parts 52, 72 with respect to the substrate W are
realized by moving the substrate W with the first and second nozzle parts
52, 72 fixedly positioned. For a relative movement of a substrate and a
nozzle, either one of them may be moved. By fixing the nozzle and moving
the substrate, pattern elements can be stably formed by preventing
dripping from discharge ports and a variation in discharge amount due to
impact or vibration applied to the nozzle.

[0040] Further, since the stripe-shaped pattern elements can be formed by
the second nozzle part 72 at the outer sides of the row of the discharge
ports 525 of the first nozzle part 52 in the Y-direction and at different
positions in the Y-direction, the pattern elements can be efficiently
formed also on an irregularly shaped substrate having a shape different
from a rectangular shape. Particularly, since the pair of discharge ports
725 in the second nozzle part 72 are positioned symmetrically with
respect to the center of the row of the discharge ports 525 in the first
nozzle part 52, pattern elements can be efficiently formed on a
substrate, the shape of which is line-symmetrical with respect to a
center line, as described below.

[0041] FIG. 3 is a diagram which shows an example of a solar cell formed
using the pattern forming apparatus of FIG. 1. This solar cell S is so
structured that a multitude of narrow finger wiring pattern elements F
and wide bus wiring pattern elements B arranged to cross the finger
wiring patterns elements F are provided on a surface (surface with a
photoelectric conversion surface and an anti-reflection layer) of the
monocrystalline silicone substrate W. The finger wiring pattern elements
F and the bus wiring pattern elements B are electrically connected at
their intersections.

[0042] Concerning dimensions of the respective parts, for example, the
width and height of the finger wiring pattern elements F may be set at
about 50 μm, the width of the bus wiring pattern elements B may be set
at 1.8 mm to 2.0 mm and the height thereof may be set at 50 μm to 70
μm. However, the dimensions are not limited to these numerical values.

[0043] The silicon substrate W has an octagonal shape which is formed by
cutting off four corners of a substantially square shape and
line-symmetrical with respect to a center axis C. This shape results from
a disk-shaped wafer cut out from a monocrystalline silicon rod produced
to have a substantially cylindrical shape and necessity to form the
substrate W effectively utilizing the surface area of the wafer.

[0044] Thus, a multitude of finger wiring pattern elements F formed on the
substrate W have a fixed length in a seemingly rectangular region RR in a
central part of the substrate W, but the finger wiring pattern elements F
in each end region ER have lengths different from each other in
conformity with the shape of the end region ER. With the conventional
technology for forming pattern elements by moving a multitude of nozzles
relative to a substrate, the substrate having such a shape could not be
coped with. Contrary to this, since application is individually
controlled in the rectangular region RR and the end regions ER in the
pattern forming apparatus 1 of this embodiment, pattern elements can be
efficiently formed also on an irregularly shaped substrate as shown in
FIG. 3.

[0045] FIG. 4 is a flow chart which shows a pattern forming process in
this pattern forming apparatus. More specifically, the pattern forming
process of FIG. 4 is a process for forming the finger wiring pattern
elements F on the octagonal substrate W as shown in FIG. 3. First, the
substrate W is loaded into the pattern forming apparatus 1 and placed on
the stage 3 (Step S101). Subsequently, the ball screw mechanism 740 is
actuated to set a distance between the two discharge nozzles 725 in the
second nozzle part 72 to a predetermined initial value (Step S102). This
will be described in detail later. In this state, the stage 3 is started
moving in the X-direction (Step S103), and the discharge of the
application liquid from the discharge nozzles 523 of the first nozzle
part 52 is started to form the finger wiring pattern elements in the
rectangular region RR (Step S104). Note that the movement of the
substrate W and the discharge of the application liquid are preferably
substantially simultaneously started to make the starting ends of the
pattern elements have a uniform cross-sectional shape.

[0046] FIGS. 5A and 5B are views which diagrammatically show formation of
the pattern elements by the first nozzle part. As shown in FIG. 5A, a
plurality of discharge nozzles 523 of the first nozzle part 52 are
arranged at equal intervals in a range corresponding to the width of the
rectangular region RR of the substrate W and a plurality of stripe-shaped
(linear) finger wiring pattern elements F1 extending in a scan-moving
direction Dn, parallel to each other and having an equal length can be
simultaneously formed by moving the first nozzle part 52 relative to the
substrate W in the scan-moving direction Dn (-X-direction) while
discharging the application liquid from the respective discharge nozzles
523.

[0047] Although not shown in FIG. 5A, the light irradiation part 53 moving
relative to the substrate W to follow the first nozzle part 52 moving
relative to the substrate W irradiates the application liquid with light
in this embodiment as shown in FIG. 1. Thus, the application liquid
immediately after being discharged from the discharge ports 525 is
successively irradiated to be cured, whereby the finger wiring pattern
elements F1 maintaining a cross-sectional shape immediately after the
discharge are formed. When the discharge ports 525 have a rectangular
opening, pattern elements having a substantially rectangular
cross-sectional shape can be formed as shown in FIG. 5B. Therefore, a
wiring pattern element with a high ratio of height Hp to width Dp of the
pattern elements, i.e. a high aspect ratio can be efficiently formed.

[0048] Referring back to FIG. 4, the pattern forming process is further
described. The relative movement of the first nozzle part 52 with respect
to the substrate W as described above is continued until the first nozzle
part 52 reaches a predetermined application end position (e.g. end of the
substrate) (Step S105). When the application end position is reached, an
application ending operation is performed (Step S106). The application
ending operation includes the stop of discharge of the application liquid
from the respective discharge ports 525, the stop of movement of the
stage 3 in the X-direction and a lowering movement of the stage 3 by the
stage elevating/lowering mechanism 24.

[0049] FIGS. 6A to 6C are diagrams which show the principle of the
application ending operation. Upon ending the discharge when the first
nozzle part 52 scan-moving along the surface of the substrate W reaches
the application end position (substrate right end), application liquid P
applied on the substrate W is continuous with the application liquid
around the discharge ports 525 or in the nozzles due to its surface
tension as shown in FIG. 6A. If the scan-movement of the first nozzle
part 52 is continued in this state, the application liquid is extended by
the discharge nozzles 523 to produce thin trails as shown in FIG. 6B or
the pattern elements may be formed beyond the application end position on
the substrate W where they should end.

[0050] In this embodiment, this is prevented by performing the application
ending operation including the stop of discharge of the application
liquid from the respective discharge ports 525, the stop of movement of
the stage 3 and the lowering movement of the stage 3. That is, as shown
in FIG. 6C, the movement of the substrate W in the X-direction is stopped
when the discharge of the application liquid from the discharge ports 525
is stopped. By further lowering the substrate W together with the stage
3, the first nozzle part 52 is relatively retracted in a direction away
from the surface of the substrate W, thereby separating the application
liquid P applied on the substrate W and the first nozzle part 52. By
linking a scan-movement and a separating movement of the first nozzle
part 52 relative to the substrate W in synchronization with a discharge
timing of the application liquid from the discharge ports 525 in this
way, the shapes of the final ends of the pattern elements can be aligned
without disturbing the application liquid on the substrate W.

[0051] By the above operations up to Step S106, a multitude of finger
wiring pattern elements F1 parallel to each other and having an equal
length are formed in the rectangular region RR on the substrate W.
Subsequently, pattern elements are formed in the end regions ER using the
second nozzle part 72. First, this is outlined.

[0052] FIGS. 7A and 7B are views which diagrammatically show formation of
pattern elements by the second nozzle part. As shown in FIG. 7A, the
pattern elements are formed in the end regions ER by discharging the
application liquid from the discharge ports 725 while moving the pair of
discharge nozzles 723 provided in the second nozzle part 72 relative to
the substrate W having the finger wiring pattern elements F1 already
formed thereon. At this time, formation positions of the pattern elements
in the Y-direction are determined by adjusting the distance between the
two discharge nozzles 723 in the Y-direction by the ball screw mechanism
740. Further, the lengths of the pattern elements are adjusted by making
a mode of scan-movements of the discharge nozzles 723 relative to the
substrate W and the discharge timing of the application liquid from the
discharge ports 725 different from those by the first nozzle part 52 to
change application start positions and application end positions on the
substrate W.

[0053] A plurality of pattern elements to be formed in the end regions ER
are formed by scan-moving the two discharge nozzles 723 relative to the
substrate W a plurality of times while changing the positions of the
discharge nozzles 723 in the Y-direction by the ball screw mechanism 740.
That is, as shown in FIG. 7A, the positions of the discharge nozzles 723
are so set that these nozzles pass right at the outer sides of the
outermost ones of the already formed wiring pattern elements F1 in the
row, thereby first forming a pair of pattern elements F21. A distance
between the two nozzles 723 at this time is equivalent to the "initial
value" in Step S102 of FIG. 4.

[0054] Subsequently, pattern elements F22, F23, . . . are successively
formed as shown in FIG. 7B by repeating scan-movements of the discharge
nozzles 723 relative to the substrate W each time while changing the
distance between the discharge nozzles 723 little by little. At this
time, the start end position, final end position and length of the
pattern elements formed by each scan-movement can be changed by changing
the application start position and application end position according to
a set value of the nozzle spacing. In this way, wiring pattern elements
corresponding to the shapes of the end regions ER can be formed. Further,
symmetric pattern elements can be formed by maintaining the two discharge
nozzles 723 at positions symmetrical with respect to the center line of
the substrate W.

[0055] This operation procedure is described with reference to the flow
chart of FIG. 4. By the process up to Step S106, the finger wiring
pattern elements F1 (FIG. 5A) are formed on the substrate W and the stage
3 carrying the substrate W is located at a middle position between a
position right below the first nozzle part 52 and a position right below
the second nozzle part 72. In following Step S107, a pair of finger
wiring pattern elements (e.g. pattern elements F21) are formed in the end
regions ER as described above by passing the stage 3 carrying the
substrate W below the second nozzle part 72 while discharging the
application liquid from the discharge ports 725 of the pair of discharge
nozzles 723 provided in the second nozzle part 72. When the positions of
the discharge nozzles 723 relative to the substrate W reach the
application end position (Step S108), the application ending operation is
performed to align the final ends of the pattern elements as in the case
of application by the first nozzle part (Step S109).

[0056] Then, whether or not formation of all the necessary pattern
elements has been completed is determined (Step S110), the distance
between the two discharge nozzles 723 provided in the second nozzle part
72 is changed and set (Step S111) and the stage 3 is returned to the
middle position (Step S112) if there are pattern elements yet to be
formed. In this state, the discharge nozzles 723 are scan-moved relative
to the substrate W to form new pattern elements (e.g. pattern elements
F22). As described above, the positions and shapes of the start ends and
final ends of the pattern elements are aligned by synchronizing the
timing of the scan-movements of the discharge nozzles 723 relative to the
substrate W and the discharge timings from the discharge ports 725 every
time each two pattern elements are formed.

[0057] When this is repeated a necessary number of times and it is
determined that all the necessary pattern elements have been formed (Step
S110), the stage 3 is moved to a predetermined substrate unloading
position and then the movement thereof is stopped (Step S113) and the
substrate W having all the finger wiring pattern elements F formed
thereon is unloaded (Step S114), thereby completing the pattern forming
process.

[0058] The bus wiring pattern elements B are subsequently formed on the
substrate W having the finger wiring pattern elements F formed thereon in
this way and the solar cell S shown in FIG. 3 can be completed by
performing a heating (fire-through) process if necessary. Formation of
the bus wiring pattern elements and the heating process are not
particularly limited and not described here since known technologies can
be applied.

[0059] As described above, in this embodiment, the finger wiring pattern
elements are formed on the octagonal monocrystalline silicon substrate.
At this time, the finger wiring pattern elements F1 parallel to each
other and having an equal length are formed in the rectangular region RR
in the central part of the substrate by scan-moving the first nozzle part
52, in which the multitude of discharge ports 525 are arranged in a row,
relative to the substrate W. On the other hand, for the end regions ER of
the substrate in which the lengths of the pattern elements to be formed
are not fixed, the second nozzle part 72 including the pair of discharge
nozzles 723, the positions of which in the Y-direction perpendicular to
the scan-moving direction (X-direction) can be changed and set, is
scan-moved relative to the substrate W. By independently performing
formation of the pattern elements in the rectangular region RR and that
of the pattern elements in the end regions ER in this way, desired
pattern elements can be efficiently formed on an irregularly shaped
substrate having a non-rectangular shape as in this example.

[0060] Further, the shapes of the start ends and final ends of the pattern
elements can be aligned by synchronizing the start and end timings of the
scan-movements of the discharge nozzles relative to the substrate W and
the discharge timings of the application liquid from the discharge ports.
In this case, application by the second nozzle part 72 is performed
independently of application by the first nozzle part 52. Thus, in this
embodiment, scan-movements and discharges can be performed at optimal
timings for pattern elements having different lengths and such pattern
elements having different lengths can be formed with good
controllability.

[0061] Further, a plurality of pattern elements are formed in the end
regions ER by making the distance between the two discharge nozzles 723
of the second nozzle part 72 changeable and repeating the scan-movement
while changing this distance. Thus, the second nozzle part 72 only has to
include the pair of discharge nozzles 723 regardless of the number of
pattern elements to be formed in the end regions ER. Therefore, the
apparatus construction is simplified.

[0062] As described above, in this embodiment, the stage 3 functions as a
"substrate holder" of the present invention. Further, the discharge ports
525 provided in the first nozzle part 52 correspond to "first discharge
ports" of the present invention, whereas the discharge ports 725 provided
in the second nozzle part 72 correspond to a "second discharge port" of
the present invention. Further, the syringe pump 521 and the manifold
part 522 in the first nozzle part 52 and the syringe pump 721 in the
second nozzle part 72 respectively function as an "application liquid
storage" of the present invention. The stage moving mechanism 2 and the
ball screw mechanism 740 function as a "mover" of the present invention.

[0063] The invention is not limited to the embodiments described above but
may be modified in various manners in addition to the embodiments above,
to the extent not deviating from the object of the invention. For
example, in the above embodiment, the finger wiring pattern elements
having different lengths are formed in the end regions ER by changing the
distance between the two discharge nozzles 723 of the second nozzle part
72 and performing a scan-movement relative to the substrate each time.
Instead of this, the following arrangement may be, for example, employed.

[0064] FIG. 8 is a diagram which shows an outline of a second embodiment
of a pattern forming apparatus according to this invention. In this
embodiment, a first nozzle part 52, a plurality of second nozzle parts
81, 82, 83, . . . , in which distances between paired discharge nozzles
(811 and 812, 821 and 822, 831 and 832) in a Y-direction differ from each
other are successively arranged in a moving direction (X-direction) of a
substrate W by a movement of a stage.

[0065] In such a construction, the discharge nozzles 811, 812, . . . , are
arranged beforehand at positions corresponding to positions of a
plurality of respective pattern elements to be formed in end regions ER.
Accordingly, nozzle positions need not be changed in the Y-direction and
desired pattern elements can be formed by simply causing the substrate W
to pass at positions facing the respective nozzle parts. Since this
embodiment can improve throughput in successively forming pattern
elements on a plurality of substrates, it is more suitable for mass
production.

[0066] Also in this case, a movement of the substrate and discharge
timings are preferably synchronized to align the shapes of the pattern
elements. The discharge timings differ when the lengths of the pattern
elements differ. Thus, even in the case of successively processing a
multitude of substrates, a movement and discharge for each substrate are
preferably independently controllable. A distance Dx between the
respective nozzle parts in the X-direction is preferably larger than
length Lw of the substrate W in the X-direction to process the respective
substrates in parallel with an independent control of movements of the
respective substrates.

[0067] Further, in the above embodiment, the finger wiring pattern
elements F1 are first formed in the rectangular region RR of the
monocrystalline silicon substrate W, subsequently the finger wiring
pattern elements F21 and the like are formed in the end regions ER and
then the bus wiring pattern elements B are formed to form the solar cell
S. However, the order of these processes is not limited to this. For
example, wiring pattern elements may be formed in the rectangular region
RR after wiring pattern elements are formed in the end regions ER.
Further, either the application start timing or the application end
timing may be simultaneous between the pattern elements to be formed in
the rectangular region RR and the pattern elements to be formed in the
end regions ER. Furthermore, a substrate having the bus wiring pattern
elements B already formed thereon may be loaded into the pattern forming
apparatus 1 to form the finger wiring pattern elements F.

[0068] Although electrodes are obtained by curing the application liquid
by irradiating light to the application liquid containing the
photo-curing resin in the above embodiments, it is not an essential
requirement that the application liquid contains the photo-curing resin
and that light is irradiated to the application liquid. Further, whether
or not to perform the heating process after application of the
application liquid is also optional.

[0069] Although the wirings are formed only on one side of the substrate W
in the above respective embodiments, the present invention can be applied
also in the case of forming wirings on both sides of the substrate W.
Further, the shape of the substrate and the number of the pattern
elements in the above embodiments are only examples, and an application
range of the present invention is not limited to these.

[0070] Although the solar cell as the photoelectric conversion device is
manufactured by forming the electrode wiring pattern elements on the
monocrystalline silicon substrate in the above respective embodiments,
the substrate is not limited to a silicon substrate. For example, the
present invention can be applied also in forming pattern elements on a
thin-film solar cell formed on a glass substrate or a device other than
the solar cell.

[0071] This invention is applicable to an apparatus and a method for
forming pattern elements on a substrate, e.g. electrode wiring pattern
elements on a solar cell substrate and can be particularly preferably
applied in the case of forming pattern elements having different lengths
on an irregularly shaped substrate having a non-rectangular shape.

[0072] In this invention, the mover may, for example, move the first
nozzle part relative to the substrate in synchronization with the
discharge of the application liquid from the first discharge ports and
move the second nozzle part relative to the substrate in synchronization
with the discharge of the application liquid from the second discharge
port. In a transient state such as when the discharge of the application
liquid is started and ended, the shapes of the pattern elements might be
disturbed since the discharge amount is not stable. This problem can be
solved by moving the first and second nozzle parts relative to the
substrate in synchronization with the discharge timings.

[0073] Further, the second nozzle part may be, for example, change and set
a position of the second discharge port in the arrangement direction can
be changed and set. In such a construction, a multitude of pattern
elements can be formed by scan-moving the second nozzle part each time
while changing the position of the second discharge port in the
arrangement direction. Particularly, if a relative movement amount of the
second nozzle part with respect to the substrate in the scan-moving
direction is changed according to the set position of the second
discharge port in the arrangement direction, pattern elements having
various lengths can be formed by the second nozzle part.

[0074] Further, a plurality of the second nozzle parts, the positions of
the second discharge ports of which differ from each other in the
arrangement direction, may be, for example, arranged. By doing so, a
plurality of pattern elements can be efficiently formed by the plurality
of second nozzle parts.

[0075] Further, a pair of the second discharge ports may be, for example,
provided at the opposite sides of the first nozzle part in the
arrangement direction. By doing so, pattern elements having different
lengths from the pattern elements formed by the first nozzle part can be
formed at the opposite sides of the latter pattern elements. Note that
the second discharge ports need to be located at the opposite sides of
the first nozzle part in the arrangement direction, but a positional
relationship between the first nozzle part and the second discharge ports
in the scan-moving direction is not limited.

[0076] In this case, the pair of second discharge ports may be arranged at
positions symmetrical with respect to the row of the first discharge
ports, and the mover may integrally move the pair of second discharge
ports relative to the substrate. In such a construction, pattern elements
can be efficiently formed on a substrate with a shape symmetrical with
respect to an axis in the scan-moving direction such as a monocrystalline
silicon substrate for solar cell.

[0077] Further, the application liquid may be, for example, supplied to
the pair of respective second discharge ports from a same application
liquid storage for storing the application liquid. By doing so, pattern
elements having the same cross-sectional shape and length can be formed
under the same condition of discharging the application liquid from the
respective second discharge ports. Similarly, the application liquid may
also be supplied to the plurality of first discharge ports from a same
application liquid storage for storing the application liquid. By doing
so, the plurality of pattern elements formed by the first nozzle part can
be made to have the same cross-sectional shape and length.

[0078] In this invention, positions of the first nozzle part and the
second nozzle part in the scan-moving direction may be fixed and the
mover may realize relative movements of the first and second nozzle parts
with respect to the substrate by moving the substrate holder holding the
substrate. In the case of moving the first and second nozzle parts
discharging the application liquid, the discharge amount of the
application liquid varies and the shapes of the pattern elements may be
disturbed due to impact and vibration applied to the nozzle parts. Such a
problem is prevented by moving the substrate without moving the first and
second nozzle parts.

[0079] Although the invention has been described with reference to
specific embodiments, this description is not meant to be construed in a
limiting sense. Various modifications of the disclosed embodiment, as
well as other embodiments of the present invention, will become apparent
to persons skilled in the art upon reference to the description of the
invention. It is therefore contemplated that the appended claims will
cover any such modifications or embodiments as fall within the true scope
of the invention.